| In millions, except per share items | Dec-31-20 | Dec-31-19 | Dec-31-18 | Dec-31-17 | Dec-31-16 | Dec-31-15 | Dec-31-14 | Dec-31-13 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 20-F | 20-F |
| Net income | -45.1 | -60.8 | 15.5 | -113.5 | -49.2 | -43.6 | -9.7 | -5.3 |
| Depreciation and amortization [+] | 5.1 | 5.1 | 7.2 | 5.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Depreciation | 0.1 | 0.1 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Amortization of intangible assets | 5.0 | 5.0 | 7.2 | 5.0 | | | | |
| Asset impairment charges | | | | 20.7 | 16.4 | 0.6 | | |
| Stock-based compensation | 7.4 | 8.6 | 7.8 | 5.2 | 4.6 | 3.9 | 0.3 | 0.7 |
| Deferred taxes | | | | 2.0 | -2.9 | -0.5 | -0.5 | -0.1 |
| Change in working capital [+] | -3.2 | 20.7 | -7.7 | 0.7 | -0.4 | 20.0 | 4.0 | 3.2 |
| Accounts receivable | -0.5 | -0.7 | 0.0 | -1.6 | | | | |
| Inventories | 1.1 | 1.6 | -3.4 | -0.5 | | | | |
| Other current assets | 0.2 | 3.1 | -3.0 | -0.4 | 0.8 | -1.2 | -0.3 | -0.1 |
| Accounts payable | -1.8 | 2.2 | -0.1 | 0.2 | -1.7 | 1.7 | 0.2 | 0.5 |
| Accrued expenses | -6.0 | -2.6 | -1.1 | 3.0 | 0.5 | 1.3 | 0.7 | 1.0 |
| Other | 3.9 | 17.2 | | | | 18.1 | 3.3 | 1.8 |
| Other operating activities | -2.3 | -18.4 | -107.4 | 34.6 | -0.2 | -17.8 | -3.6 | -2.0 |
| Cash from operations | -38.1 | -44.8 | -84.6 | -45.3 | -31.7 | -37.4 | -9.5 | -3.5 |
| |
| Capital expenditures | 0.0 | -0.1 | -0.3 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Purchases of property and equipment | 0.0 | -0.1 | -0.3 | | | 0.0 | 0.0 | 0.0 |
| Sales of short-term investments, net [+] | 21.1 | -20.7 | | | | | | |
| Purchases of short-term investments | | -56.2 | | | | | | |
| Sales of short-term investments | 21.1 | 35.5 | | | | | | |
| Other cash from investing | | | 134.7 | -7.5 | -3.4 | -4.3 | | |
| Cash from investing | 21.1 | -20.8 | 134.3 | -7.5 | -3.4 | -4.3 | 0.0 | 0.0 |
| |
| Issuance of common stock, net | 28.6 | | 42.1 | 26.4 | 32.3 | | | 14.9 |
| Option exercises | | 0.2 | 0.1 | 0.6 | 0.1 | | | |
| Other cash from financing | 18.9 | 0.3 | -26.8 | 17.8 | 18.1 | 77.4 | 10.2 | |
| Cash from financing | 47.5 | 0.1 | 15.2 | 43.5 | 50.3 | 77.4 | 10.2 | 14.9 |
| |
| Free cash flow | -38.1 | -44.9 | -84.9 | -45.3 | -31.7 | -37.4 | -9.5 | -3.5 |
| Per share (diluted) | ($0.66) | ($0.81) | ($1.71) | ($1.24) | ($1.46) | ($2.25) | ($1.18) | ($0.58) |
| |
| Cash paid for interest | 0.6 | | 11.1 | 2.9 | 0.0 | | | |
| Cash paid for income taxes | 0.7 | 0.4 | 0.0 | 0.1 | | | | |